Actors' Equity Association, the actors' union, has defined the undefinable je ne sais quoi that makes a "star" in deciding that British actor Michael Gambon is one, and thus may recreate his London role in David Hare's drama Skylight when it comes to Broadway Sept. 19.

Under union rules a "star" may recreate a role on Broadway without objection, but non-stars must be replaced by American actors unless an exchange is worked out so the same number of American actors can appear in Britain.

Daily Variety reported that Equity ruled Gambon -- known to U.S. audiences, if at all, from PBS' airing of the "Singing Detective" -- indeed met its five criteria for stardom. These are: Star billing in the past; Worked in "theatres of renown," drawn a salary "commensurate with stardom," gotten reviews "indictative of stardom," and is planning to take a starring role in an impending production.

So now you know. The Daily Variety story said Gambon's co-star Lia Williams will get to appear with him on Broadway owing to an exchange agreement, and a third character will be cast with an American TBA.